Device for sorting material according to granular size and weight



Dec. 3, 1963 H. SCHMITZ 3,113,099

DEVICE FOR SORTING MATERIAL ACCORDING TO GRANULAR SIZE AND WEIGHT Filed Feb. 8, 1961 4 Sheets-Sheet 1 Dec. 3, 1963 Filed Feb. 8, 1961 H. SCHM DEVICE FOR SORTING MATERIAL ACCORDING TO lTZ 3,1 13,099

GRANULAR SIZE AND WEIGHT I 4 Sheets-Sheet ,2

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ATTORNEY Dec. 3, 1963 H. SCHMITZ 3,113,099

DEVICE FOR SORTING MATERIAL ACCORDING TO GRANULAR SIZE AND WEIGHT Filed Feb. 8. 1961 4 Sheets-Sheet 3 INVENT OR A'lTOR NEY Dec. 3, 1963 H. SCHMITZ 3,113,099

DEVICE FOR SORTING MATERIAL ACCORDING TO .GRANULAR SIZE AND WEIGHT Filed Feb. 8, 1961 4 Sheets-Sheet 4 Fig.5

INVENTOR ATTORNEY United States Patent Ofiice 3-,ll3,fifill Patented Dec. 3, 1963 3,113,099 DEVIE FOR SORTING MATEREAL ACCQRDING T GRANULAR SlZE AND WElGHT Hugo Schmitz, Becltum, Westphalia, Germany, assignor to Polysius G.m.b.H., Neubeelrum, Germany Filed Feb. 8, 1961, Ser. No. 87,960 Claims priority, application Germany Feb. 15, 1960 12 Claims. (Cl. sea-r35 The present invention relates to a classifier or apparatus for separating and sorting granular and pulverous material. In my co-pending application Ser. No. 22,190, filed April 14, 1960, there has been described an apparatus of the just mentioned general type in which a mixture of the material to be classified is together with air passed through a diliuser. In the said difiuser, the speed of the air is reduced by providing a section with increased cross section. Due to this reduction in speed of the air, also the fine particles in the air stream which follow the latter have their speed reduced, whereas the larger particles due to their greater mass and consequently higher kinetic energy overcome the frictional resistance of the air and consequently lose only little of their speed. At the exit end of the diffuser the speed of the larger particles is considerably higher than that of the air.

The particles of difierent size thus differ from each other at the exit of the diffuser in their speed. After the air has left the 'ditiuser, it can be deviated laterally. This deviation is again followed by the fine particles which hardly carry out any relative movement to the air flow, Whereas the larger particles are not at all or only slightly deviated from their direction of movement. In conformity with the arrangement described in my said co-pending application, the fine particles will then be separated from the air in a cyclone or other separator following the classifier.

-It is an object of the present invention to provide an improved classifier which will yield a sharper separation of the fine material from the coarse material.

It is another object of this invention to provide a classifier system of greater compactness so as to require a minimum of space for the classifier and separator for the fine material.

These and other objects and advantages of the invention will appear more clearly from the following specification in connection with the accompanying drawings, in which:

FIG. 1 is a diagrammatic illustration of the entire classifier-separator system.

FIG. 2 is a diagrammatic longitudinal section through a classifier according to the present invention.

FIG. 3 is a diagrammatic longitudinal section through a modified classifier according to the invention.

FIG. 4 is a horizontal section through the upper part of the whirling device 2, said section being taken along the line AA of FIG. 2; and

FIG. 5 represents an enlargement of the central right hand portion of FIG. 2.

The classifier according to the present invention is characterized primarily in that the separation of the coarser and finer materials from each other is effected by a combination of a diffuser effect and a cyclone effect.

According to a further development of the invention, the separator for the fine material which according to my co-pending application follows the classifier, is in coniormity with the present invention built into the classifier so that no additional separator outside the classifier is required. The advantages of such an arrangement as to compactness and space will be obvious.

According to the arrangement described in my above mentioned co-pending application, the material-air mixture is when employing an axially symmetrical diffuser,

supplied centrally to the diffuser passage. With this classifier structure, the particles of different sizes move in the direction of flow through the diffuser while the particles are distributed over the diffuser cross section in an at-random arrangement. An improvement in the classifying effect will be obtained if it is possible to impart upon the particles in the diffuser not only a different speed but in addition thereto to impart upon the particles such a speed that the particles will have certain paths of movement in the diffuser passage depending on the respective sizes of the particles.

When the particle mixture flows in such a way that the particles are not arranged as to granular size, the particles will move in a disordered arrangement over the entire cross section at a speed which is particular to their respective sizes. In this instance, so to speak, several groups of particles pass through the flow passage because the air, since it affects lighter particles more strongly than heavy particles, acts like a screen and tends to separate the particles according to size and weight. Each of these groups consists of particles of substantially the same size which therefore have the same speed. Those groups which contain the finest particles will have the lowest speed which will substantially correspond to the speed of the air. The groups having the largest particles will correspondingly have the highest speed. it will be evident that these groups moving at dif erent speeds will continuously impinge upon each other and thereby eifect their movement so that coarse particles impinge upon fine particles which will then stick to the larger particles. This will lead to a falsification of the granular picture of the later separated fractions.

In order to overcome this drawback, according to a further development of the present invention, the material to be classified is prior to its entering the diffuser uniformly distributed in the air stream by any suitable devices, and the thus obtained material-air mixture is rotated prior to entering the diffuser. The means for a uniform distribution of the material in the air stream and for effecting the rotation of the material-air mixture does not form a part of the present invention and may be of any standard design as it is well-known in the art. It will be appreciated that in this way a spiral flow of the air and the material will be effected in. the diffuser.

The well-known laws governing hydrodynamics also apply to the movement of the particles in a spiral-shaped air flow. Accordingly, with the larger particles, the centrifugal forces dominate, whereas with the smaller particles the frictional forces of the air stream containing same will dominate. Thus, the larger particles will, similar to the situation in a cyclone becentrifuged outwardly, whereas the finer particles which cannot or only slightly overcome the frictional forces of the air stream will remain more on the inner fiow paths. These laws also apply to the movement of the particles in the whirling device and in the subsequent accelerator and diffuser passage.

The location of the particles in the flow passage is dependent on the steepness of the air spiral in axial direction and on the absolute speed of the air flow. Therefore, in conformity with a further development of the invention, the width of the fiow passage is adjustable by adjusting the outer end or inner cone walls to thereby produce different spiral flows.

Referring now to the drawings in detail and FIG. 1 thereof in particular, the material to be classified is passed through a rotary trap 1 and a device 2 for causing whirling of the gas into the classifier generally designated 3. Prior to entering the classifier 3, the material to be classified has added thereto air which is furnished by a blower 4- drivingly connected to a motor 5 and furnishing the air through a pipe 7 into the whirling device 2.

The bottom of the classifier 3 is provided with a separator comprising a pipe 8 through which the classified coarse material is passed through a rotary trap 9, while the classified finer material is passed through a pipe 10 into a cyclone 11 and from there to a rotary trap 12.

The classifier itself may be designed for instance in the manner illustrated in FIG. 2. According to the embodiment shown in FIG. 2, the classifier comprises a stationary housing 13 which has substantially the shape of a double cone. Arranged within said housing is a core generally designated 14 which is adjustable in axial direction of said housing and has a likewise double cone shape. The wall portion 14a of the core wall is substantially parallel to the wall portion 13a of the housing 13 and together therewith forms the diffuser 27.

As will be evident from FIG. 2, core 14 is suspended on a hollow spindle 15 having connected thereto a hand Wheel 16 for axial adjustment of the hollow spindle 15. Arranged within said hollow spindle is a further spindle 17 which extends through core 14 and has a funnel 18 connected thereto. Funnel 18 divides the outer opening of the diffuser passage into outer and inner annular openmgs.

The upper end of spindle 17 has connected thereto a hand wheel 19 by means of which the spindle 17 and funnel 18 can be lifted and lowered.

The lower end of funnel 13 telescopically engages the pipe 10 which is fixedly connected to the housing 13 and guides said funnel. Spindle 17 assures the position of core 14 relative to the housing 13.

According to FIG. 2, the material to be classified passes through chute 21 into charging pipe 22 and from there into the device 2. Air enters the device 2 through a pipe connection 23 which leads tangentially into the device 2 so that the air entering said device will be subjected to a spiral movement. The charging pipe 22 may be provided with slots or guiding panels 24 and 25 in order to obtain a thorough mixing of the material to be classified with the air. Within the housing 2a of the device 2 the material will be carried along by the air and will be loosened and in this condition be moved into the accelerating passage 26. As indicated above, due to the tangential feeding of the air into the device 2, the air-material mixture will pass through the accelerating passage 26 and the adjacent diffuser 27.

The air passes through the accelerating passage 26 at approximately constant speed because the shape of said accelerating passage is so designed that it furnishes everywhere substantially the same fiow cross section. The decrease in the width of the passage 26 toward the diffuser 27 thus corresponds to the increasing diameter. The particles passing from the device 2 into the accelerating passage will be accelerated in the latter. It will be appreciated that while the fine particles will already in the device 2 be brought up to the speed of the air, the larger particles due to their greater inertia require a longer path to this effect. At the entrance 27a into the diffuser 27, the large and small particles have approximate air velocity.

Due to the centrifugal field created by the spiral movement of the air stream in the device 2 and in the accelerator, the particles in the air stream are additionally subjected to a centrifugal acceleration. This centrifugal acceleration has different effects upon the large and small particles respectively. Whereas, the larger particles in view of their greater inertia are centrifuged outwardly, the fine particles which follow the frictional forces of the air stream are retained on the inner flow paths. Thus, the particles sort themselves in the air stream according to their size while preferably the larger particles accumulate along the outer wall of the flow passage.

The said sorting according to the size of the particles Will also be retained in the diffuser passage 27 because also in this diffuser passage 27 a spiral-shaped flow prevails. However, even though in the diffuser the spiralshaped flow gradually merges into a straight flow, the

sorting of the particles will be maintained because the larger particles due to their own kinetic energy have the tendency to flow straight ahead in the same direction, i.e. along the outer wall 13a of the housing 13. The free fall speed to which the coarse particles are likewise subjected and which, in certain circumstances, could cause said coarse particles to change their direction of flow, is so small with regard to the high speeds in the classifier that they are irrelevant for all practical purposes. The particles pass through the entire flow passage within fractions of a second.

At the exit from the diffuser, the air is drawn inwardly into the inner annular opening. The fine particles follow this deviation of the air flow, whereas the coarser particles do not and rather move along the outer diffuser wall into the outer annular opening and retain their original direction of movement inasmuch as the coarser particles relatively easily overcome the frictional resistance at the point of deviation of said air stream. Thus, the coarser parcles first move along the extension of the outer diffuser wall and then drop into the collecting chamber 28.

The air and the fine particles carried along by the latter will, after leaving the diffuser, pass through the collecting chamber 29 which is formed by the funnel 18 and the lower counter cone 14b of the core 14. The finer particles pass through pipe 10 into the separator 11 (cyclone) which may be of any standard type.

At the deviating station 39, the particles carried by the air stream are exposed to the frictional forces of the deviated air stream. This frictional resistance acts upon the particles in the manner of a screen. Large particles will, due to their greater inertia and higher speed, overcome said frictional resistance. However, the finer particles, which are unable to overcome said frictional resistance, will be carried along by the deviated air stream. It will be appreciated that if the frictional resistance is changed, this will bring about a displacement of the separating borders. The frictional resistance in its turn is dependent on the flow velocity of the air. For this reason, in conformity with the present invention, the air velocity may be controlled by various means at the deviating station. Thus, by adjusting the funnel 18 in axial direction thereof, the velocity at which the air flows into the collecting chamber 29 may be controlled. This, however, is possible only within certain limits because the entrance velocity is dependent primarily on the quantity of air and the speed thereof when leaving the diffuser.

In order to be able to vary the air velocity at the deviating station within wider limits, according to a further development of the invention, the outer wall 13a is provided with a slot 13!; extending over the entire circumference. This slot has associated therewith an annular slide 31 equipped with adjusting screws 32 for arresting the slide in its respective position. The said slot may be opened to a different degree or closed by correspondingly adjusting said annular slide. It will be appreciated that said slot is arranged precisely at said deviating station. When said slot 13!) is open, air from the outside enters the classifier in which sub-atmospheric pressure prevails, and by correspondingly adjusting said annular slide it is possible to control the influx of additional air by which the air velocity of the deviated air stream will be increased. Therefore, also a larger proportion of the entire material will be pulled along by the air stream, and the separating border will be displaced toward the coarse grain side.

In addition to the above, the slot 13b has a further advantageous effect. Inasmuch as the air stream entering through said slot fiows transverse through the flow of material coming from the diffuser and passes through the entrance opening of the collecting chamber 29, this air stream is adapted to clean the coarser particles from possible dust adhering thereto and to carry away said dust together with the air.

With the arrangement described in my above mentioned co-pending application Ser. No. 22,190, a separator, as for instance a cyclone, is connected to the exit of the classifier for separating the fine material from the air. Such an additional separator is also necessary in connection with the embodiment illustrated in FIG. 2 of the present invention.

In order to obtain a further improvement and simplification of the structure shown in FIG. 2, the embodiment of FIG. 3 is provided according to which the separator is contained within the classifier.

More specifically, with reference to FIG. 3, according to the arrangement shown therein, the chamber 33 formed by the collecting funnel 34 is designed as a cyclone. T 0 this end, near the entrance into said chamber 33 there are provided guiding panels 35 which force the air intermixed with fine material to carry out a rotary movement in the funnel 34. The air which flows together with the material through the device 2, the accelerator 26 and the difiuser 27, will in the same manner as described in connection with FIG. 2 carry out a spiral-shaped movement. However, as experience has shown the air which is braked in the diffuser will lose a considerable portion of its speed in tangential direction. The guiding panels 35 thus serve to increase the velocity of the air in tangential direction.

Thus, in the funnel 34 there will be produced a centrifugal force field which is dependent on the air velocity in tangential direction and is furthermore dependent on the diameter of the funnel at the various levels. With decreasing diameter, the centrifugal forces of the flow field will increase. Due to the funnel-shaped form of the separator, it will be obtained that the centrifugal field which brings about the separation will be particularly strong in the lower portion of the funnel.

In order to assure that possibly all particles to be separated will enter the range of the said strong centrifugal field, a guiding wall 36 may be provided. The particles which have been centrifuged out in the funnel-shaped separator 34 will then slide downwardly along the funnel wall into a discharge pipe 37 which has connected thereto an air-tight discharging device (not shown in the drawings) of any standard structure. The air stream freed from fine material will be discharged in the direction of the arrow A through the air discharge pipe 38.

In order to be able to impose upon the air to be discharged from the separator a controlled direction of flow, a displacement body 39 may be arranged within the fun nel 34. The coarse particles will, similar to the embodiment of FIG. 2, collect in the chamber 40 surrounded by the lower portion of the housing 41 and will be discharged through chute 42.

It is, of course, to be understood that the present invention, is, by no means, limited to the particular constructions shown in the drawings but also comprises any modifications within the scope of the appended claims.

What I claim is:

1. In an apparatus for classifying lighter and heavier particles of a granular mixture: an outer conical member, an inner conicall member arranged in spaced axially adjustable relationship to and within said outer conical member and confining therewith diffuser passage means having an inlet opening adjacent its smaller diameter portion and having an outlet opening adjacent its larger diameter portion, said members being non-rotatively mounted, accelerator means having an outlet communicating with said difiuser passage means at the smaller diameter portion thereof, said accelerator means also having an inlet, a chamber with inlet means for receiving the granular material to be classified and with outlet means communicating with the inlet of said accelerator means, said chamber also including an inlet connection leading substantially tangentially into said chamber for admitting a carrier gas under pressure into said chamber to loosen up and intermix with the granular material to be classified while imparting a spiral movement upon said gas-granular mixture and conveying the same to said accelerator means and diffuser passage means, said outlet opening being lo cated at the radially inner side of the space between said members for withdrawing air and fine particles from the diffuser passage in a direction toward the axis of the diffuser, and means for causing flow of gas from said diffuser passage means into said outlet.

2. An apparatus according to claim 1, in which each of said conical members has the shape of a double cone.

3. In an apparatus for classifying lighter and heavier particles of a granular mixture: an outer conical member, an inner conical member arranged in spaced relationship to and within said outer conical member and confining therewith diifuser passage means having an inlet opening adjacent its smaller diameter portion and having an outlet opening adjacent its larger diameter portion, said members being stationarily mounted, accelerator means preceding said diifuser passage means and communicating with the inlet opening thereof, means for setting up a whirling action in gas supplied to said diffuser comprising a chamber communicating with said accelerator means and having inlet means for receiving the granular material to be classified and also having an inlet connection leading substantially tangentially into said chamber for admitting a carrier gas under pressure into said chamber to loosen up and intermix with the granular material to be classified while imparting a spiral movement thereon and conveying the thus spirally moving gas-granular mixture into said accelerator means and into said diffuser passage means, first collecting means communicating with the outlet opening of said diffuser passage means and including means forming a first annular opening arranged adjacent the outer wall of said diffuser passage means for collecting the heavier particles of said mixture, and second collecting means likewise communicating with said outlet opening of said diffuser passage means and including means forming a second annular opening arranged adjacent the inner wall of said diffuser passage means for collecting the lighter classified particles from said mixture, and means for causing flow of gas and the said lighter particles from said diffuser passage means in a direction toward the axis of said diifuser and into said second annular opening.

4. An apparatus according to claim 3, in which the outer wall of said first collecting means forms an extension of said outer conical member and tapers downwardly from the latter, and in which chute means is provided connected to the lower end of said first collecting means for receiving the classified material therefrom.

5. An apparatus according to claim 3, in which said collecting means includes an annular element between said annular openings and which includes means for adjusting said annular element in axial direction of said conical members.

6. In an apparatus for classifying lighter and heavier particles of a granular mixture: a stationary housing having a conical section, a stationary conical member spaced from and arranged within said conical section and confining therewith diffuser passage means having an inlet opening adjacent the smaller diameter portion of said conical section for receiving the granular mixture to be classified intermixed with a carrier gas, said diffuser passage means also having an outlet arranged adjacent the larger diameter portion of said conical section, means in communication with said inlet opening for imparting upon said gas-granular mixture a spiral movement and conveying the thus spirally moving gas-granular mixture into said diffuser passage means including a chamber and a supply connection leading substantially tangentially into said chamber, an annular member in said outlet opening dividing it into outer and inner annular openings, said outer annular opening forming a part of a first collecting means communicating with said outlet opening of said dilfuser passage means and arranged adjacent the outer wall of said difiuser passage means for collecting the heavier particles of said mixture, and said inner annular opening comprising a part of a second collecting means likewise communicating with said outlet opening of said ditfiuser passage means but arranged adjacent the inner Wall of said difiuser passage means for collecting the lighter classified particles from said mixture, the outer wall of said diffuser passage means having a slot therethrough arranged adjacent said outlet opening and within the range where said second collecting means communicates with said outlet opening for the passage of air from the outside into said apparatus, and means for withdrawing air from said ditfuser passage means into said inner annular opening.

7. An apparatus according to claim 6, which includes control means associated with said slot for varying the effective opening thereof.

8. In an apparatus for classifying lighter and heavier particles of a granular mixture: an outer conical member, an inner conical member arranged in spaced relationship to and Within said outer conical member and confining therewith diffuser passage means having an inlet opening adjacent its smaller diameter portion and having an outlet opening adjacent its larger diameter portion, accelerator means preceding said diffuser passage means and communicating with the inlet opening thereof, means including a chamber communicating with said accelerator means and having inlet means for receiving the granular material to be classified and also having an inlet connection leading substantially tangentially into said chamber for admitting a carrier gas under pressure into said chamber to loosen up and intermix with the granular material to be classified while imparting a spiral movement there- 'on and conveying the thus spirally moving gas-granular mixture into said accelerator means and into said diffuser passage means, collecting means including an annular inlet communicating with the outlet opening of said diffuser passage means adjacent the outer wall of said diffuser passage means for collecting the heavier particles of said mixture, and cyclone means likewise including an annular inlet communicating with said outlet opening of said diffuser passage means adjacent the inner wall of said diffuser passage means for collecting the lighter classified particles and air intermixed therewith, said cyclone means having waste air conduit means extending upwardly through the central portion of said inner conical member and through said chamber, means for causing movement of air from said diffuser passage means into the said annular inlet of said cyclone separator means.

9. In an apparatus for classifying lighter and heavier particles of a granular mixture: an outer conical memher, an inner conical member arranged in spaced relationship to and within said outer conical member and confining therewith diffuser passage means having an inlet 7 opening adjacent its smaller diameter portion and having an outlet opening adjacent its larger diameter portion,

accelerator means preceding said diffuser passage means and communicating with the inlet opening thereof, means including a chamber communicating with said accelerator means and having inlet means for receiving the granular material to be classified and also having an inlet connection leading substantially tangentially into said chamber for admitting a carrier gas under pressure into said chamber to loosen up and intermix with the granular material to be classified while imparting a spiral movement thereon and conveying the thus spirally moving gas-granular mixture into said accelerator means and into said diffuser passage means, collecting means including an annular inlet communicating with the outlet opening of said di-ffuser passage means adjacent the outer wall of said diffuser passage means for collecting the heavier particles of said mixture, cyclone separator means having an annular inlet adjacent to and communicating with said outlet opening of said diffuser passage means but adjacent the inner wall of the latter for collecting the lighter classified particles and air intermixed therewith, said cyclone separator means having waste air conduit means extending upwardly through the central portion of said inner conical member and through said chamber, means for causing movement of air from said diffuser passage means into the said annular inlet of said cyclone separator means, and guide blade means arranged behind said inlet of said cyclone separator means for imparting a rotary motion to the gas passing through the cyclone inlet thereby to increase the cyclone effect in said cyclone separator means.

10. An apparatus according to claim 9, in which said cyclone separator means is provided with a central downwardly directed guide wall means to guide all particles to be separated into the range of the particularly strong centrifugal force field in the lower portion of said cyclone separator means.

11. An apparatus according to claim 9, in which said means for causing movement of air into the inlet of said cyclone separator means comprises a blower having its suction side connected to said waste air conduit means.

12. An apparatus according to claim 9, in which said means for causing movement of air into the inlet of said cyclone separator means comprises a blower having its suction side connected to said waste air conduit means, said lblower having its outlet connected to said inlet connection to said chambers.

References Cited in the file of this patent UNITED STATES PATENTS 1,818,905 McGee Aug. 11, 1931 2,381,954 Hardinge Aug. 14, 1945 2,773,598 Castellani Dec. 11, 1956 FOREIGN PATENTS 1,181,399 France Jan. 5, 1959 

1. IN AN APPARATUS FOR CLASSIFYING LIGHTER AND HEAVIER PARTICLES OF A GRANULAR MIXTURE: AN OUTER CONICAL MEMBER, AN INNER CONICAL MEMBER ARRANGED IN SPACED AXIALLY ADJUSTABLE RELATIONSHIP TO AND WITHIN SAID OUTER CONICAL MEMBER AND CONFINING THEREWITH DIFFUSER PASSAGE MEANS HAVING AN INLET OPENING ADJACENT ITS SMALLER DIAMETER PORTION AND HAVING AN OUTLET ADJACENT ITS LARGER DIAMETER PORTION, SAID MEMBERS BEING NON-ROTATIVELY MOUNTED, ACCELERATOR MEANS HAVING AN OUTLET COMMUNICATING WITH SAID DIFFUSER PASSAGE MEANS AT THE SMALLER DIAMETER PORTION THEREOF, SAID ACCELERATOR MEANS ALSO HAVING AN INLET, A CHAMBER WITH INLET MEANS FOR RECEIVING THE GRANULAR MATERIAL TO BE CLASSIFIED AND WITH OUTLET MEANS COMMUNICATING WITH THE INLET OF SAID ACCELERATOR MEANS, SAID CHAMBER ALSO INCLUDING AN INLET CONNECTION LEADING SUBSTANTIALLY TANGENTIALLY INTO SAID CHAMBER FOR ADMITTING A CARRIER GAS UNDER PRESSURE INTO SAID CHAMBER TO LOOSEN UP AND INTERMIX WITH THE GRANULAR MATERIAL TO BE CLASSIFIED WHILE IMPARTING A SPIRAL MOVEMENT UPON SAID GAS-GRANULAR MIXTURE AND CONVEYING THE SAME TO SAID ACCELERATE MEANS AND DIFFUSER PASSAGE MEANS, SAID OUTLET OPENING BEING LOCATED AT A RADIALLY INNER SIDE OF THE SPACE BETWEEN SAID 